Windows 7: In Waterfox and Firefox is a bug on tooltips ???

Hi



In Waterfox and Firefox is a bug on tooltips. When i maked in my popup.css in my theme border-radius: 16px then is in the addon manager and errorconsole a trancparency background !!! I will this runded i found not a code for this problem i have all other code testet see snapshot !!!



Here my code in my popup.css:

tooltip {
color: #000;
font: message-box;
max-width: 50em;
margin-top: 21px;
padding: 4px 5px;
border: 1px solid #808080;
background-color: #c0c0c0;
border-radius: 16px;
text-align: center;
}

Can you help me thanks for all !!!
Sorry for my english im come from germany !!! ;-)